Transmission issue?

I just noticed this today. I have an 03 double cab auto trans. In 4th gear decelerating about 50mph once the rpms drop below about 1900 my vehicle begins to shake and it feels like the transmission is slipping. It only does this in 4th gear which is weird to me. I know nothing about transmissions so any advice would help!

 

If in true decel (no throttle), you couldn't feel 'slip'.

If feathering throttle at that RPM, TC could be locking/unlocking.

Is the fluid full? Bright pink, fresh smell? Last time is was serviced?

 

I'd do a drain and fill with new fluid firat and see if it goes away. Sounds like a TQ cinverter issue though.

 

Agree on replacing the TC
No codes?

 

if you tap the brakes the torque converter should unlock if it is locked, you might be able to test your theory that way.

 

Yeah it's like right at where it wants to downshft into 3rd is when it's happening. I have no idea when fluid was last changed. What does TC stand for and how would I change it

 

I'm only asking because I've looked this up on Google and something came up that mentioned the throttle control position sensor and I wasn't sure if you were talking about TC meeting that or torque converter here is the link
://www.google.com/amp/s/repairpal.com/automatic-transmission-may-not-shift-correctly-at-high-mileages-105.amp

 

Take the truck to a reputable transmission shop for a free test drive
You can watch the torque converter locking and unlocking on a quality scanner
Road tests are free
https://www.tacomaworld.com/threads...sions-write-up-your-4-speed-automatic.325531/

This would be a guess without a road test and a scanner
http://www.sonnax.com/parts/3517-oversized-secondary-pressure-regulator-valve-kit#needthisif

 

TC = Torque Converter.

But maybe that's a better idea to change the Throttle position sensor and the 3 shift solenoids first. Shift solenoids can be changed at the same time you change the tranny filter.....and the filter sounds like something you should do also.

If changing the throttle position sensor/filter/3 shift solenoids does not fix it then do the TC.
see this link .....my symptoms are a little different then yours but the TC can have different foot prints.
changing the 3 solenoids https://www.yotatech.com/forums/f2/tranny-issues-p0770-s-o-s-294937/